This invention relates to holders or nests for replaceable disposable cutting inserts used in cutting tools and, more particularly, to such inserts of the pin-type having circular apertures centrally disposed therein.
A cutter for pin-type replaceable cutting inserts of the above-mentioned type is disclosed in my U.S. Pat. No. 3,788,625. That cutter includes peripheral, radially extending recesses in which the replaceable disposable inserts are received. A holder or nest is positioned in each recess adjacent the back face of the insert, the insert being retained on an integral pin extending from the front face of the holder and by a lip formed by a chip clearance cut out at the front of the recess. A keying lug on the back face of the holder is received in a keyway in the recess and includes a screw threadedly receivable in the cutter body. The screw serves to clamp the holder and the insert in the recess with the cutting face of the insert being engaged by the lip.
The construction shown in the above-mentioned patent poses a problem in the case of small diameter cutters which may provide insufficient back-up or support for the holder. The provision of the keying lug on the back face of the holder necessarily increases the circumferential dimension of the holder and insert assembly. Where the cutter body itself is of small diameter, there may be insufficient material to accommodate the keying lug.
It is thus the primary object of the present invention to provide an insert holder or nest for pin-type replaceable cutting inserts that will obviate the necessity for a keying lug on the back face of the holder and consequently, the necessity for a keying recess or keyway extending circumferentially thereof.
It is a further object of the present invention to provide an insert holder or nest for pin-type replaceable cutting inserts that will provide a screw means receiving extension on the holder which extension is coplanar with the back face of the holder, whereby the circumferential extent of the holder and insert assembly is minimized.
It is a still further object of the present invention to provide a holder or nest for pin-type replaceable cutting inserts that will comprise axially extending screw receiving means coplanar with the back face of the holder to minimize the circumferential extent of the required recess as, for example, in rotary cutters of small diameter.
It is a still further object of the present invention to provide a holder or nest for pin-type replaceable cutting inserts which will achieve precise location of the insert as respects the work-facing surface of the cutting tool.